1. Field of the Invention
The invention relates generally to enclosures and, more particularly, to an extension assembly for increasing the depth of an enclosure, such as for example, an electrical enclosure. The invention also relates to enclosures employing extension assemblies.
2. Background Information
Buildings, such as for example, commercial buildings and residences, typically have an electrical distribution center with one or more enclosures, such as for example, boxes or cabinets, which house electrical equipment (e.g., without limitation, relays; circuit breakers; meters; transformers).
For example, FIG. 1 shows an electrical enclosure 2 (e.g., without limitation, a panel board; a control center; a load center) which collectively houses the circuit breakers 22 for branch circuits (not shown) at a site served by an electric power distribution system (not shown). The electrical enclosure 2 includes a housing 4 which is recessed to be substantially flush with a wall surface 6. A trim assembly 8 is mounted on the front of the housing 4 by a picture frame structure 10. The trim assembly 8 includes a trim piece 12 which supports a hinged door 14 and a dead front 16. The dead front 16 is accessible when the hinged door 14 is open, as shown, and includes openings 18,20 through which portions of the branch circuit breakers 22 and a main circuit breaker 24 protrude.
In replacing or updating electrical service infrastructure provided by older electrical enclosures (e.g., enclosure 2), it has been discovered that the physical size of the new or different electrical equipment to be installed is sometimes different than the prior equipment but that the enclosures are otherwise still adequate. It is, therefore, desirable to continue to use the same enclosure and, rather than replacing it, retrofit it with a new interior and circuit breakers. This is particularly true, for example, in the case of recessed panel boards where costly repairs would probably be required to remove and replace the panel board. Retrofitting old enclosures with new interiors and circuit breakers has traditionally required, for example, shimming up the replacement interior or fabricating new risers to bring new smaller circuit breakers into registry with the dead fronts of the enclosures. The latter practice requires the contractor to supply measurements of the existing enclosure, which are often not accurate and/or not timely provided.
One prior proposal for attempting to overcome the foregoing disadvantages with respect to retrofitting and updating existing electrical enclosures has been to provide an adjustable riser assembly 26 like the one shown in FIG. 2. The riser assembly 26 can be adjusted in the field in height and/or in depth in the directions indicated by arrows 28,30, respectively, in order to retrofit the enclosure 2 with a replacement or expanded interior 32. Adjustable riser assemblies are discussed in greater detail, for example, in U.S. Patent Application Publication No. 2006/0028789 entitled “Adjustable Riser and Panel Board Incorporating Same,” filed Aug. 6, 2004, which is hereby incorporated herein by reference.
Although adjustable riser assemblies have solved some of the issues concerning size and depth of electrical enclosures, additional problems remain. Among them is the fact that there traditionally has been no recourse if the electrical enclosure was too shallow for the intended application. Specifically, some relatively new electrical components such as, for example, circuit breakers are designed to have a relatively thin and long structure in order to fit increased numbers of breakers beside one another within the same amount of space. Where the depth of such components is greater than the depth of the electrical enclosure such that the enclosure was not deep enough to accommodate them, there has been no known suitable solution other than to completely remove and replace the enclosure.
Additionally, with regard to new electrical enclosures, it is desirable to minimize the amount of variation from electrical enclosure to electrical enclosure during manufacture. In other words, rather than custom designing each enclosure to meet a precise depth specification, which is cost-intensive, it would be more efficient to manufacture a universal enclosure and a mechanism which can be used with such universal enclosure to adapt (e.g., without limitation, add depth) it, as necessary, in order to provide the desired depth for the particular application at hand.
There is a need, therefore, for a mechanism to add depth, as necessary, to new and existing enclosures.
There is, therefore, room for improvement in enclosures, such as, for example, electrical enclosures.